You were just cleared on an instrument approach and you have to fly a procedure turn. Do you know what fix you're supposed to "remain within 10NM" of?

What's So Confusing?

When you read an instrument approach chart, you'll often find a published procedure turn. It's a course reversal to help you line yourself up on the final approach course of an instrument approach. These procedure turns are flown in the direction indicated by the graphically depicted barbed arrow.

Headings are provided for course reversals using the 45 degree type procedure turn, but you do have more options, including the teardrop procedure turn, and the 80 degree/260 degree course reversal. We'll dive into these specifics in another article soon.

The point which you begin turning, the type of turn, and the rate of turn is left up to you. You must, however, fly no farther away than the published "Remain within __NM" distance during your turn. This is a note on the chart's profile view. If you exceed the maximum distance, you're no longer guaranteed terrain or obstacle clearance based on the procedure turn's minimum altitude.

This is where the confusion starts. What point/fix/navaid is this maximum distance based off of?

The Answer? It's In The FAA's Aeronautical Chart User's Guide.

While not explicitly stated in the Aeronautical Information Manual (AIM) or the Instrument Flying Handbook (IFH), the answer is subtly found in the Aeronautical Chart User's Guide under the title "Instrument Approach Procedures (Charts)."

If you take a look at the profile view for instrument approaches, there is a label called "Procedure Turn (PT) Fix." The accompanying arrow points to an example fix, in this case the "AB LOM," or the "AB Locator Outer Marker." Maximum distance for the procedure turn is based upon this fix. It may be the navaid for the approach, the final approach fix, or any other designated fix.

Pay Close Attention To The Variety Of PT Fixes

Reading the wrong DME could leave you flying in unprotected airspace, too close to nearby terrain or obstacles. Let's run through a few examples.

First, lets look at the ILS or LOC to RWY 4 at Southwest Oregon Regional (KOTH) below. The PT fix is designated as the EMPIRE LOM, which is 6.3 DME from North Bend VOR (OTH). The EMPIRE LOM also happens to the be the FAF for the approach. Note that DME for fixes along this approach are based on the VOR, not on the localizer itself. The chart says you must "remain within 10NM" for this procedure turn. This means you can fly a maximum of 16.3 DME away from the OTH VOR during your procedure turn, which is the same as flying 10NM away from the EMPIRE LOM.

Next, let's take a look at the VOR RWY 35L in Grand Forks, ND (KGFK) below. The PT fix is now the GFK VOR itself. Notice how there's no FAF published on the approach? You must remain within 10NM of the VOR itself during the procedure turn, or 10DME from GFK on your avionics. There's one step-down fix for aircraft that can identify ELVAW. When using this fix as a step-down, you can descend an additional 140 feet to an MDA of 1220 feet MSL.

This approach in particular is a little tricky because of the 10NM limitation. Most approaches give you more distance to get established, since the PT fix corresponds with the FAF. Because the VOR is the PT fix, the procedure turn must be completed several miles closer to the airport than usual.

Ready for even more complexity? Take a look at the ILS or LOC to RWY 12 at the Brookings Regional Airport, SD (KBKX) below. The approach requires an ADF to fly the procedure turn from an enroute segment. The PT fix is both the FAF for the approach, 7 DME from the I-BKX Localizer, and is the also the "CHRLZ NDB." This NDB happens to be a Compass Locator (CL).

When making the procedure turn, you can fly a maximum of 10 DME from CHRLZ. This is the same as flying 17 DME from the I-BKX LOC. Because the ADF is required, you're required to use DME readouts from the CHRLZ Compass Locator, the PT Fix.

If you use Jeppesen charts, understanding this get's a whole lot easier (keep reading to find out why).

There Are Exceptions, Of Course.

According to the AIM, "pilots should begin the outbound turn immediately after passing the procedure turn fix. The procedure turn maneuver must be executed within the distance specified in the profile view. The normal procedure turn distance is 10 miles. This may be reduced to a minimum of 5 miles where only Category A or helicopter aircraft are to be operated, or increased to as much as 15 miles to accommodate high performance aircraft."

While rare, pay special attention the published maximum distance for your procedure turn in case it falls under one of these exceptions.

Do You Fly Approaches Using Jeppesen Charts?

Jeppesen approach charts are slightly different from FAA government charts. Jeppesen charts remove most of the confusion by clarifying which point the maximum distance is related to. On the same VOR RWY 35L into KGFK that we looked at earlier, the Jeppesen chart labels the procedure turn maximum distance as "10NM from VOR" directly on the chart.

Similarly, the Jeppesen chart clarifies the complexity we covered at KBKX. The note in the profile view clearly states "10NM from CHRLZ"

Make Sure You're Using The Right Distance

When you're flying a procedure turn, you need to make sure you're getting your distance information from the right source.

In rare cases, an amendment or NOTAM could change the procedure turn maximum distance. If that's the case, you need to make sure you're following the NOTAM distance, not the distance on the chart. Until a new, updated chart database is available, it's your responsibility to ensure you don't fly beyond the maximum published distance.

The designated PT fix on approach charts is always used as point-zero for a procedure turn's maximum distance.

What do you think? Have you ever been confused by this? Tell us in the comments below.